Page:Land Mollusca of North America (north of Mexico) Vol. I Part 1 277-end.pdf/12

 4500 feet,1 and in Madera Canyon. Also in the southwestern Santa Ritas and the Pajaritos.

Fig. 158. Sonorella walkeri (type of S. montana P. & F.).

This fine snail is not uncommon in the Santa Ritas, though less generally distributed than S. santaritana. The type locality. Walnut Canyon, is humid, and well shaded with decidious trees. S. walkeri lives in piles of granitic rock with S. santaritana and S. clappi, sometimes all under the same rock, sometimes in separate rock piles. The smallest specimens, topotypes, measure 20 mm. in diameter; the largest, from Madera canyon, 24.3 mm.

Many specimens have been dissected. The slender, short penis, with a short, thick basal sheath, and the enlarged free vas deferens are conspicuous characters. The smaller umbilicus and less depressed contour separate it from S. santaritana, which also differs more fundamentally by its genitalia. S. walkeri is very much like S. clappi in soft anatomy, but the shells are quite distinct. It is closely related to S. huachucana. perhaps to be united with that as a subspecies, the most tangible difference being that the penis is smaller. In the Santa Ritas it inhabits higher and much more humid places than huachucana.

In the " Allen Mountains", Station 206 (1919), a small group of hills in Josephine Canyon, in the south- western foothills of the Santa Ritas towards the San Cayetanos, fine, large specimens, about 25.5 mm. in diameter, were taken by Ferriss and Hinkley. Length of penis 2.5, verge 1.3, epiphallus 5, vagina 12 mm.; the flagellum is vestigial, penial retractor long. I have not been able to locate these " mountains " on the map.

1 Soldier Canyon is a small canyon running in north of the mouth of Agua Caliente, opening to the mesa between two high crags. The rock is a coarse granite, and shells are not numerous. A single giant cactus growing here is further east than we have seen the species elsewhere.

Fig. 159. Sonorella walkeri (montana). p. penis; pr., penial retractor; sp.d., duct of spermatheca.

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